AP Physics 1 · Unit 4 · Momentum

Conservation of Momentum Practice Problems

Choose the objects in your system, then track momentum through collisions and releases. Practice carts that stick, a moving thrower and catcher, vehicle impacts, spring recoil, and modules separating in two directions.

12 questions6 conceptual · 6 calculation

Start practice

Free · No account required · Self-paced

Simulation scene from the Conservation of Momentum lesson. — A scene from the related lesson. Open the practice to work through the questions.

What you’ll practice

Choose a system and follow its momentum

Check the external impulse

Explain why taking a step changes one person’s momentum and how the ground belongs in a larger system. Distinguish internal transfers from an outside impulse.

Follow collisions and exchanges

Add the initial momentum of every object. Solve a sequence of sticking collisions, a moving throw, a catch, and different occupant velocity changes during a vehicle impact.

Analyze recoil and component balances

Compare spring forces on unequal masses, calculate opposite recoil velocities, and conserve x and y momentum independently during a planar release.

A question from this set

A step and the system boundary

A person initially at rest takes a step to the right on level ground. Does the person’s new momentum contradict conservation of momentum?

Yes. Momentum conservation prevents a person from starting to move.
No. The ground gives the person an external impulse; the person–Earth system receives equal and opposite internal impulses.
No. A person’s momentum stays zero even while the person moves.

Try it in the practice set

The person and ground interact. Choosing one object or both changes which forces cross the system boundary.

Key ideas

Conservation belongs to a chosen system

Internal impulses transfer momentum between objects

Equal and opposite internal impulses cancel in the complete system. The individual objects can change momentum while the system total remains constant when net external impulse is zero.

Sticking adds a shared-velocity condition

For objects that remain together, add their masses in the final momentum term. Momentum can stay constant while kinetic energy becomes internal energy. A spring release can instead increase kinetic energy using stored energy.

See the physics

Watch the parts change while the total stays fixed

After checking an answer or calculation parts, run the prepared collision or release. Compare recorded momentum traces for each object with the system total, switch the three-cart collision order, and examine separate component graphs for a planar release.

Use a hint for a starting point or open a worked solution to follow the reasoning. Your progress saves in this browser, so you can return to unfinished questions.

Ready for conservation of momentum?

Begin with a conceptual question, then work through the calculations.

Start practice